Discarded hypodermic syringes present a serious health hazard. It is not unusual for people to be accidentally pricked by a syringe after use, and to so become infected with a disease transmitted from the person for whom the syringe was originally used. For example, personnel cleaning up hospital spaces or doctors' offices frequently must pick up numerous such syringes after use, and it is very easy to be accidentally stuck by the syringes when doing this. Furthermore, used hypodermic syringes frequently disposed of in plastic garbage bags, which are readily pierced by the syringes so that these are exposed and can easily prick a person who is handling the garbage. Also, municipal garbage is frequently dumped at sea, and there have been cases where syringes have washed up on the beach, where they may be stepped on by barefoot strollers. The seriousness of this problem has grown significantly with the spread of the Acquired Immune Deficiency Syndrome (AIDS) virus.
Some attempts have been made to eliminate the problem of accidental injury from used hypodermic syringes. For example, devices have been provided which cut or snap the metal syringe off from the plastic body of the syringe, both to prevent its re-use, and to also retain the severed syringe in a suitable, relatively thick-walled disposal container. While this provides a relatively satisfactory solution for many facilities, it is not without its drawbacks. For example, hospitals and many doctors' offices have a great many treatment rooms, and it is expensive and often simply not practical to install such a syringe clipping device in each of these rooms for the relatively occasional use which it will receive. More seriously, paramedics and other emergency response personnel who must administer injections at an accident or other emergency scene obviously cannot be burdened with carrying an additional piece of equipment in the form of a syringe clipper, and, in any event, they typically do not have time to use such a device; this problem is seriously aggravated at many accident sites, such as an automobile accident where the paramedic must work in a confined space or lie on the ground in a close proximity with the used hypodermic syringes, and so be at increased risk of accidental injury due to being pricked by one of these. A similar situation is faced by military medical personnel in combat situations, and also in military field hospitals.
Accordingly, there exists a need for a hypodermic syringe which provides for protection against injury due to persons being pricked by the needle after use, without requiring a separate device for doing this. Furthermore, there is a need for a syringe having such a provision which is inexpensive to manufacture and simple to operate.